1. Field of the Invention
The present invention relates to compositions of binders. Most advantageously the invention can be used for manufacturing concrete and reinforced concrete products.
It is well known that the properties and parameters of a binder determine the physical and chemical properties of concrete as well as the cost thereof. Therefore many attempts have been made to improve binder compositions.
2. Description of the Prior Art
Known in the art are binders comprising granulated slag and compounds of alkali metals.
For manufacturing said binders, use is made of granulated blast furnace slags and electrothermophosphoric slags having a specific surface of not more than 300 m.sup.2 /kg. Used as compounds of alkaline metals are carbonates, fluorides, hydroxides and, most widely, sodium silicates and potassium silicates which are soluble glasses.
Such binders are very active, and concrete stone based thereon possesses high corrosion resistance, cold resistance, water impermeability, heat resistance, air resistance, water resistance, adhesion to fillers, reinforcement etc. They solidify in the air and in water and possess high hydraulic properties (V. D. Gluhovsky et al. Shchelochnyie i shelochno-zemelnyie gidravlicheskie viazhushchie i betony, Kiev, Vyshcha shkola Publishers, pp. 103-104).
However, because of considerable variations of chemical, mineralogical and phase composition of slags the prior art binders gain strength slowly. Therefore said binders are not used as quick-hardening binders.
In addition, cement stone based on such binders in some cases possesses increased shrinking deformation and increased time of damping thereof as compared to portland cement stone.
There is also known in the art a binder disclosed in USSR Inventor's Certificate No 408,928 and comprising in % by weight:
______________________________________ granulated blast furnace slag 55.5 to 61.0 soluble glass 29.0 to 33.0 portland cement 10.0 to 11.0 ______________________________________
To obtain the above binder, the granulated blast furnace slag is preliminarily grinded until the specific surface of the slag is 2,800 to 3,000 cm.sup.2 /g and then mixed with the portland cement. Thereafter the obtained mixture is sealed by an alkali component. The alkali component is a solution of sodium (or potassium) glass having a modulus of 1.8 to 2.3 and a density of 1.3 to 1.35 g/cm.sup.3 in an amount of 40 to 43% of the weight of dry components.
The tests of the prior art binder have shown that the activity thereof both at early stages of solidification and later is low. In addition, the prior art binder gains strength slowly. Thus, the compressive strength of the prior art binder in one day is 10.6 MPa, and in 28 days, 32.6 MPa.
This is due to the fact that the binder comprises portland cement which contains gypsum intensifying the solidification process. The gypsum reacts with the alkali component and neutralizes it, which results in the formation of salts. This reduces the content of the alkali component in the binder, which brings about a decrease in the activity and atmospheric durability thereof.